1. Field of the Invention
The present invention relates to a light emitting diode control system, and especially relates to a light emitting diode control system using modulated signals.
2. Description of the Related Art
Nowadays, the connection types of the light emitting diode lamp string modules are separated into two types: the serial-type connection and the parallel-type connection. The light emitting diode lamp string modules are widely used for external walls of the building, decoration of trees, signboards, and scenery designing.
The related art light emitting diode lamp string modules are commonly employed to be connected in series. Also, the amount of the light emitting diode lamp string modules is determined according to the volume of the decorated objects. In addition, all of the light emitting diode lamp string modules are controlled by the same controller which initially controls the first light emitting diode lamp string module.
Although the light emitting diode lamp string modules are easily connected together, the remaining light emitting diode lamp string modules behind the abnormal light emitting diode lamp string module cannot be lighted even only one of the light emitting diode lamp string modules is abnormal. That is because the control signal cannot be sent to drive all of the remaining light emitting diode lamp string modules.
The parallel-type light emitting diode lamp string modules are connected to the controller in parallel. Accordingly, each one of the light emitting diode lamp string modules is controlled by the controller through a control line and an address line, respectively. For example, ten control lines and ten address lines need to be used when ten light emitting diode lamp string modules are employed to be connected in parallel.
The remaining light emitting diode lamp string modules can still be normally controlled when one of the light emitting diode lamp string modules is abnormal. However, the amount of the control lines and the address lines increase proportionally. Therefore, complexity and the costs of the equipment also increase when the amount of the light emitting diode lamp string modules increases.
No matter the connection type of the light emitting diode lamp string modules is the serial-type or the parallel-type, many power transmission lines and signal transmission lines need to be used to control the colors and intensities of the light emitting diode lamp string modules. Accordingly, cost down can be achieved only if the amount of the power transmission lines or the signal transmission lines can be reduced.